79 research outputs found
Regenerative pulsations in semiconductor etalon due to competition between carrier generation and heating effects on band filling
Resonant-state expansion of the Green's function of open quantum systems
Our series of recent work on the transmission coefficient of open quantum
systems in one dimension will be reviewed. The transmission coefficient is
equivalent to the conductance of a quantum dot connected to leads of quantum
wires. We will show that the transmission coefficient is given by a sum over
all discrete eigenstates without a background integral. An apparent
"background" is in fact not a background but generated by tails of various
resonance peaks. By using the expression, we will show that the Fano asymmetry
of a resonance peak is caused by the interference between various discrete
eigenstates. In particular, an unstable resonance can strongly skew the peak of
a nearby resonance.Comment: 7 pages, 7 figures. Submitted to International Journal of Theoretical
Physics as an article in the Proceedings for PHHQP 2010
(http://www.math.zju.edu.cn/wjd/
Pseudo-time Schroedinger equation with absorbing potential for quantum scattering calculations
The Schroedinger equation with an energy-dependent complex absorbing
potential, associated with a scattering system, can be reduced for a special
choice of the energy-dependence to a harmonic inversion problem of a discrete
pseudo-time correlation function. An efficient formula for Green's function
matrix elements is also derived. Since the exact propagation up to time 2t can
be done with only t real matrix-vector products, this gives an unprecedently
efficient scheme for accurate calculations of quantum spectra for possibly very
large systems.Comment: 9 page
Time Asymmetric Quantum Physics
Mathematical and phenomenological arguments in favor of asymmetric time
evolution of micro-physical states are presented.Comment: Tex file with 2 figure
The Hyperspherical Four-Fermion Problem
The problem of a few interacting fermions in quantum physics has sparked
intense interest, particularly in recent years owing to connections with the
behavior of superconductors, fermionic superfluids, and finite nuclei. This
review addresses recent developments in the theoretical description of four
fermions having finite-range interactions, stressing insights that have emerged
from a hyperspherical coordinate perspective. The subject is complicated, so we
have included many detailed formulas that will hopefully make these methods
accessible to others interested in using them. The universality regime, where
the dominant length scale in the problem is the two-body scattering length, is
particularly stressed, including its implications for the famous BCS-BEC
crossover problem Derivations and relevant formulas are also included for the
calculation of challenging few-body processes such as recombination.Comment: 66 pages, 33 figure
Quantum-mechanical and semiclassical study of the collinear three-body Coulomb problem: Inelastic collisions below the three-body disintegration threshold
Regenerative pulsations in semiconductor etalon due to competition between carrier generation and heating effects on band filling
Competition between carrier concentration and effective temperature effects on the dielectric function of a degenerate semiconductor in a spectral range near its fundamental absorption edge is suggested as a mechanism for regenerative pulsations in a stationary pumped optical etalon. The origin of self-pulsations is similar to that in a bistable etalon with competing concentration and thermal optical nonlinearities, but, due to its purely electronic nature, the proposed mechanism provides a way for a much higher repetition frequency, probably in the GHz range. The model of the phenomenon and modeling examples are all related to a Fabry–Perot resonator filled with the bulk n+-In0.53Ga0.47As as an active medium
Principles of Geocryology (Permafrost Studies). Part I, General Geocryology. Chapter X, Ground Water in Permafrost Areas. p. 328-364
Peer reviewed: NoNRC publication: Ye
Mobility of Radiogenic Isotopes 4Не and 3Не and Their Retention in a Mineral (by the Example of Amphibole)
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